Toxicological Review of n-Hexane (CAS No. 110-54-3) (PDF)

diseases affecting the nervous system or from risk factors for alterations in nervous system
function. Urine samples, taken at the end of the shift, were all in excess of the recommended
ACGIH BEI of 5 mg/L 2,5-hexanedione, with a mean of 11.02 ± 4.5 (range 5.3 to 24.2) mg/L.
The neurological findings in these workers were compared with those obtained during the
previous 8 years in healthy adults of a similar age who were not occupationally exposed to any
toxic substance. No significant anomalies were identified in neurological examinations or
worker responses to questionnaires about neurophysiological problems. However, the results of
electrographic evaluations showed significant decreases in the amplitude of sensory nerve action
potential (SNAP) for the median, sural, and ulnar nerves. These results were unrelated to urinary
2,5-hexanedione levels. However, the SNAP amplitude for the sural and median nerves was
significantly related to the number of years exposed to n-hexane. Adjusting for age did not alter
these results. No differences were found in values of the SCV, MCV, compound muscle action
potential, and F wave latency (a more precise indication of small variations in conduction) for
the nerves evaluated.
Murata et al. (1994) studied the effects of solvent exposure on the autonomic nervous
system and cerebellar function in shoe and leather workers exposed to n-hexane, xylene, and
toluene. 2,5-hexanedione, hippuric acid, and methylhippuric acid concentrations in urine
samples (taken the morning prior to electrophysiological examination) were determined.
Urinary concentrations of 2,5-hexanedione were 0–3.18 (mean 1.39) mg/L; concentrations of
hippuric acid were 0.05–2.53 (mean 0.41) g/g creatinine; and concentrations of methylhippuric
acid were 0.10–0.43 (mean 0.19) g/g creatinine for occupationally exposed workers. In
unexposed workers, the urinary concentration of 2,5-hexanedione was 0.1–0.8 g/g creatinine and
hippuric acid was < 1.5 g/g creatinine; methylhippuric acid was not found. Exposure
concentrations for n-hexane, xylene, or toluene were not reported by the study authors. The
study subjects were free of known confounding factors related to nervous system function and
were similar in their reported use of alcohol and tobacco. Exposed workers had worked in
household factories for a period of 18–42 years (31 ± 6 years). Murata et al. (1994) measured
the distribution of MCVs and SCVs of the median nerve and the variation in the
electrocardiographic duration of the ventricular cardiac cycle (R-R interval) in 30 workers and in
25 healthy controls unexposed to solvents. The SCV and MCV of the median nerve were
significantly slowed in exposed workers compared with unexposed. Variations in the R-R
interval and the respiratory sinus arrhythmia component of the R-R interval also were
significantly lower in the exposed group. The SCV in the forearm was significantly correlated to
the variation in the Mayer sign wave arrhythmia component of the R-R interval. Duration of
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